GSO filters are made of high quality, solid plane parallel glass with excellent homogeneity. They are anti-reflection coated to prevent glaring and ghosting. All eyepiece filters are threaded to fit GSO and most other manufacturers 1.25" eyepieces and offer a full 26mm clear aperture.

#21 Orange - 46% VLT

An orange filter helps increase contrast between light and dark areas, penetrates clouds, and assists in detecting dust storms on Mars. Orange also helps to bring out the Great Red Spot and sharpen contrast on Jupiter.